Composition, electrolyte solution, polymer electrolyte, electrochemical device, and fluoropolyether

Abstract

The purpose of the present disclosure is to provide: a composition that is capable of improving high-temperature durability of an electrochemical device; an electrolyte solution; a polymer electrolyte; an electrochemical device; and a fluoropolyether. The present disclosure relates to a composition containing a salt and at least one fluoropolyether represented by any one of formulae (1) to (3). (1) R1-O-Ra1-Rb1-O-Ra1-R1; (2) R2-Rb2-O-Ra2-Rb2-R2; (3) R3-Rb3-O-Ra3-R3

Description

Composition, electrolyte, polymer electrolyte, electrochemical device, and fluoropolyether

[0001] The present disclosure relates to compositions, electrolytes, polymer electrolytes, electrochemical devices, and fluoropolyethers.

[0002] BACKGROUND ART With the recent trend toward lighter and smaller electrical appliances, the development of electrochemical devices such as lithium ion secondary batteries with high energy density has been progressing.

[0003] As a technique relating to electrochemical devices, Patent Document 1 discloses a liquid composition containing a specific (per)fluoropolyether.

[0004] Special table 2019-523529 publication

[0005] An object of the present disclosure is to provide a composition, an electrolyte, a polymer electrolyte, an electrochemical device, and a fluoropolyether that can improve the high-temperature durability of an electrochemical device.

[0006] The present disclosure (1) is a composition containing at least one fluoropolyether represented by any one of the following formulas (1) to (3) and a salt: (1) R １ -O-Ra １ -Rb １ -O-Ra １ -R １ (2) R ２ -Rb ２ -O-Ra ２ -Rb ２ -R ２ (3) R ３ -Rb ３ -O-Ra ３ -R ３ (In the formula, Ra １ ~Ra ３ are each independently a polyoxyalkylene group containing 4 to 50 oxyalkylene units and not containing fluorine, １ ~Ra ３ Each oxyalkylene unit is independently —CH ２ CH ２ O- or -CH ２CH(J)O—, each J is independently an alkyl group or an aryl group, and Rb １ ~Rb ３ are each independently a fluoropolyether group represented by the following formula (4), １ and R ３ are each independently a fluorine atom, an alkyl group having 1 to 3 carbon atoms, an aryl group, a carboxylic acid group, or a fluoroalkyl group having 1 to 3 carbon atoms, ２ are each independently a hydrogen atom, a hydroxyl group, a fluorine atom, an alkyl group having 1 to 3 carbon atoms, an aryl group, a carboxylic acid group, or a fluoroalkyl group having 1 to 3 carbon atoms. １ -Rf-O-Rf ２ - (wherein, Rf １ and Rf ２ are each independently an alkylene group having 1 to 16 carbon atoms which may be substituted with a fluorine atom, and Rf is a divalent fluoropolyether group.

[0007] The present disclosure (2) is １ ~Ra ３ are each independently a polyoxyalkylene group represented by the following formula (Ra-I): (Ra-I): —(CH ２ CH ２ O)r(CH ２ CH (CH ３ )O)s(CH ２ CH (CH ２ CH ３ )O)t(CH ２ CH(Ph)O)u- (wherein r, s, t, and u each independently represent an integer of 0 or 1 or greater, and r+s+t+u is 4 to 50.)

[0008] The present disclosure (3) is １ ~Ra ３ The composition according to the present disclosure (1) or (2), wherein the number average molecular weight of

[0009] The present disclosure (4) is the composition according to any one of the present disclosures (1) to (3), wherein each Rf is independently a fluoropolyether group represented by the following formula (Rf-I): Formula (Rf-I): -(OC ６ F １２ ) a-(OC ５ F １０ ) b-(OC ４ F ８ ) c-(OC ３ Rc ６ ) d-(OC ２ F ４ ) e-(OCF ２ )f- (In the formula, each Rc is independently a hydrogen atom, a fluorine atom, or a chlorine atom; each a, b, c, d, e, and f is independently an integer of 0 to 200; the sum of a, b, c, d, e, and f is 1 or more; the order of the repeating units assigned with a, b, c, d, e, or f is arbitrary; and when all Rc's are hydrogen atoms or chlorine atoms, at least one of a, b, c, e, and f is 1 or more.)

[0010] The present disclosure (5) is the composition according to any one of the present disclosures (1) to (4), wherein each Rf is independently a group represented by the following formula (Rf-II) or the following formula (Rf-I-II): Formula (Rf-II): -(OC ３ F ６ ) d-(OC ２ F ４ )e- (wherein d is an integer of 1 to 200, and e is 0 or 1) Formula (Rf-I-II): -(OC ４ F ８ ) c-(OC ３ F ６ ) d-(OC ２ F ４ ) e-(OCF ２ )f- (In the formula, c and d each independently represent an integer of 0 to 30, e and f each independently represent an integer of 1 to 200, the sum of c, d, e and f is 2 or more, and the order of the repeating units assigned with c, d, e or f is arbitrary.)

[0011] The present disclosure (6) is １ ~R ３are each independently a methyl group, an ethyl group, a trifluoromethyl group, or a pentafluoroethyl group.

[0012] The present disclosure (7) is the composition according to any one of the present disclosures (1) to (6), wherein the salt is a lithium salt.

[0013] The present disclosure (8) is the composition according to any one of the present disclosures (1) to (7), wherein the content of the salt is 0.1 to 30 mass%.

[0014] The present disclosure (9) is a composition according to any one of the present disclosures (1) to (8), which is liquid at any temperature between 25°C and 80°C.

[0015] The present disclosure (10) is the composition according to any one of the present disclosures (1) to (9), in which the content of the polyalkylene oxide represented by the following formula (5) is less than 20 mass %. (5) R １Ｂ -(OCHR １Ａ (CH ２ ) jCHR ２Ａ ) n-OR ２Ｂ (In the formula, R １Ａ and R ２Ａ are each independently a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, j is an integer of 0 or 1 or 2, and R １Ｂ and R ２Ｂ are each independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and n is an integer of 5 to 1000.

[0016] The present disclosure (11) is an electrolyte solution containing the composition according to any one of the present disclosures (1) to (10).

[0017] The present disclosure (12) has an ionic conductivity of 1.0 × 10 －７ ~1.0 x 10 －３ The electrolyte solution according to the present disclosure (11) has a conductivity of 1.5 S / cm.

[0018] The present disclosure (13) is the electrolyte solution according to the present disclosure (11) or (12), in which the Li ion transport number is 0.2 to 0.5.

[0019] The present disclosure (14) is a polymer electrolyte containing the electrolytic solution according to any one of the present disclosures (11) to (13).

[0020] The present disclosure (15) is an electrochemical device comprising the electrolyte solution according to any one of the present disclosures (11) to (13) or the polymer electrolyte according to the present disclosure (14).

[0021] The present disclosure (16) is a fluoropolyether represented by the following formula (2A): (2A)R ２ -Rb ２ -O-Ra ２ -Rb ２ -R ２ (In the formula, Ra ２ is a polyoxyalkylene containing 4 to 50 oxyalkylene units and not containing fluorine; ２ Each oxyalkylene unit is independently —CH ２ CH ２ O- or -CH ２ CH(J)O—, each J is independently an alkyl group or an aryl group, and Rb ２ are each independently a fluoropolyether group represented by the following formula (4A), ２ are each independently a hydrogen atom, a hydroxyl group, a fluorine atom, an alkyl group having 1 to 3 carbon atoms, an aryl group, a carboxylic acid group, or a fluoroalkyl group having 1 to 3 carbon atoms. １ -Rf-O-Rf ２ - (wherein, Rf １ and Rf ２ are each independently an alkylene group having 1 to 16 carbon atoms which may be substituted with a fluorine atom, and Rf is a divalent fluoropolyether group.

[0022] The present disclosure (17) is ２ is a polyoxyalkylene group represented by the following formula (Ra-I), and each Rf is independently a group represented by the following formula (Rf-II) or (Rf-I-II): (Ra-I): —(CH ２ CH ２ O)r-(CH ２ CH (CH ３ )O)s-(CH ２ CH (CH ２CH ３ )O)t-(CH ２ CH(Ph)O)u- (wherein r, s, t, and u are each independently an integer of 0 or 1 or more, and r+s+t+u is 4 to 50.) Formula (Rf-II): -(OC ３ F ６ ) d-(OC ２ F ４ )e- (wherein d is an integer of 1 to 200, and e is 0 or 1) Formula (Rf-I-II): -(OC ４ F ８ ) c-(OC ３ F ６ ) d-(OC ２ F ４ ) e-(OCF ２ )f- (In the formula, c and d each independently represent an integer of 0 to 30, e and f each independently represent an integer of 1 to 200, the sum of c, d, e and f is 2 or more, and the order of the repeating units assigned with c, d, e or f is arbitrary.)

[0023] According to the present disclosure, it is possible to provide a composition, an electrolytic solution, a polymer electrolyte, an electrochemical device, and a fluoropolyether that can improve the high-temperature durability of an electrochemical device.

[0024] The present disclosure will be specifically described below.

[0025] <Composition> The present disclosure relates to a composition containing at least one fluoropolyether represented by any one of the following formulas (1) to (3) and a salt: (1) R １ -O-Ra １ -Rb １ -O-Ra １ -R １ (2) R ２ -Rb ２ -O-Ra ２ -Rb ２ -R ２ (3) R ３ -Rb ３ -O-Ra ３ -R ３ (In the formula, Ra １ ~Ra ３are each independently a polyoxyalkylene group containing 4 to 50 oxyalkylene units and not containing fluorine, １ ~Ra ３ Each oxyalkylene unit is independently —CH ２ CH ２ O- or -CH ２ CH(J)O—, each J is independently an alkyl group or an aryl group, and Rb １ ~Rb ３ are each independently a fluoropolyether group represented by the following formula (4), １ and R ３ are each independently a fluorine atom, an alkyl group having 1 to 3 carbon atoms, an aryl group, a carboxylic acid group, or a fluoroalkyl group having 1 to 3 carbon atoms, ２ are each independently a hydrogen atom, a hydroxyl group, a fluorine atom, an alkyl group having 1 to 3 carbon atoms, an aryl group, a carboxylic acid group, or a fluoroalkyl group having 1 to 3 carbon atoms. １ -Rf-O-Rf ２ - (wherein, Rf １ and Rf ２ are each independently an alkylene group having 1 to 16 carbon atoms which may be substituted with a fluorine atom, and Rf is a divalent fluoropolyether group.

[0026] The composition of the present disclosure has the above-described structure, and therefore can improve the high-temperature durability (particularly, the high-temperature cycle performance) of electrochemical devices.

[0027] Furthermore, while conventional electrolyte solutions tend to be highly flammable, the composition of the present disclosure is flame-retardant and has higher electrochemical stability than conventional electrolyte solutions, thereby improving the ease of handling of electrochemical devices. Furthermore, the composition also has good ionic conductivity and transport number.

[0028] Furthermore, fluoropolyethers usually have low salt solubility and therefore do not have sufficient ionic conductivity, making them difficult to use as a solvent for an electrolytic solution. However, the fluoropolyethers represented by any of the above formulae (1) to (3) can dissolve salts and have sufficient ionic conductivity, making them usable as a solvent for an electrolytic solution.

[0029] Ra １ ~Ra ３ The oxyalkylene unit is -CH ２ In the case of CH(J)O-, the alkyl group for J may be linear or branched, but is preferably linear. The alkyl group for J preferably has 1 to 3 carbon atoms. Examples of the aryl group for J include a phenyl group, a 4-nitrophenyl group, a 4-acetylaminophenyl group, and a 4-methanesulfonylphenyl group.

[0030] Ra １ ~Ra ３ are each independently a polyoxyalkylene group represented by the following formula (Ra-I): (Ra-I): —(CH ２ CH ２ O)r-(CH ２ CH (CH ３ )O)s-(CH ２ CH (CH ２ CH ３ )O)t-(CH ２ CH(Ph)O)u- (wherein r, s, t, and u each independently represent an integer of 0 or 1 or greater, and r+s+t+u is 4 to 50.)

[0031] In the above formula (Ra-I), r is preferably 1 or more, more preferably 2 or more, and preferably 30 or less, more preferably 20 or less. s, t, and u are preferably 10 or less, more preferably 5 or less, and even more preferably 0. r+s+t+u is preferably 1 or more, more preferably 2 or more, and preferably 20 or less, more preferably 10 or less.

[0032] Ra １ ~Ra ３ The number average molecular weight of the polymer is preferably 40 or more, more preferably 100 or more, and is preferably 4000 or less, more preferably 1000 or less. １ ~Ra ３ The number average molecular weight of １ This is a value measured by H-NMR.

[0033] Rb １ ~Rb３ In the formula (4), Rf １ and Rf ２ The alkylene group of Rf may be linear or branched, but is preferably linear. １ and Rf ２ The alkylene group of Rf is preferably a fluorine-substituted alkylene group substituted with a fluorine atom. １ and Rf ２ The alkylene group preferably has 1 to 3 carbon atoms.

[0034] Rb １ ~Rb ３ In the above formula (4), Rf may have a ring structure.

[0035] Rb １ ~Rb ３ In the formula (4), Rf is preferably a fluoropolyether group represented by the following formula (Rf-I): Formula (Rf-I): -(OC ６ F １２ ) a-(OC ５ F １０ ) b-(OC ４ F ８ ) c-(OC ３ Rc ６ ) d-(OC ２ F ４ ) e-(OCF ２ )f- (In the formula, each Rc is independently a hydrogen atom, a fluorine atom, or a chlorine atom; each a, b, c, d, e, and f is independently an integer of 0 to 200; the sum of a, b, c, d, e, and f is 1 or more; the order of the repeating units assigned with a, b, c, d, e, or f is arbitrary; and when all Rc's are hydrogen atoms or chlorine atoms, at least one of a, b, c, e, and f is 1 or more.)

[0036] Rc is preferably a hydrogen atom or a fluorine atom, and more preferably a fluorine atom. That is, Rf in formula (4) is preferably a perfluoropolyether group.

[0037] Preferably, a, b, c, d, e and f are each independently an integer of 0 to 100.

[0038] The sum of a, b, c, d, e, and f is preferably 5 or more, more preferably 10 or more, and may be 15 or more or 20 or more. The sum of a, b, c, d, e, and f is preferably 100 or less, more preferably 60 or less, and may be 50 or less or 30 or less.

[0039] Each repeating unit to which a, b, c, d, e, or f is assigned may be linear or branched. ６ F １２ )- is, for example, -(OCF ２ CF ２ CF ２ CF ２ CF ２ CF ２ )-,-(OCF(CF ３ )CF ２ CF ２ CF ２ CF ２ ) -, -(OCF ２ CF (CF ３ )CF ２ CF ２ CF ２ ) -, -(OCF ２ CF ２ CF (CF ３ )CF ２ CF ２ ) -, -(OCF ２ CF ２ CF ２ CF (CF ３ )CF ２ ) -, -(OCF ２ CF ２ CF ２ CF ２ CF (CF ３ ))-. ５ F １０ )- is, for example, -(OCF ２ CF ２ CF ２ CF ２ CF ２ )-,-(OCF(CF ３ )CF ２ CF ２ CF ２ ) -, -(OCF ２CF (CF ３ )CF ２ CF ２ ) -, -(OCF ２ CF ２ CF (CF ３ )CF ２ ) -, -(OCF ２ CF ２ CF ２ CF (CF ３ ))-. ４ F ８ )- is, for example, -(OCF ２ CF ２ CF ２ CF ２ )-,-(OCF(CF ３ )CF ２ CF ２ ) -, -(OCF ２ CF (CF ３ )CF ２ ) -, -(OCF ２ CF ２ CF (CF ３ )) -, -(OC(CF ３ ) ２ CF ２ ) -, -(OCF ２ C (CF ３ ) ２ )-,-(OCF(CF ３ )CF(CF ３ ))-,-(OCF(C ２ F ５ )CF ２ ) -, -(OCF ２ CF (C ２ F ５ ))-. ３ F ６ )-(that is, in the above formula (Rf-I), when all Rc's are fluorine atoms), can be represented by, for example, -(OCF ２ CF ２ CF ２ )-,-(OCF(CF ３ )CF ２ ) -, -(OCF ２ CF (CF ３ ))-. ２ F ４ )- is, for example, -(OCF２ CF ２ )-,-(OCF(CF ３ ))-.

[0040] Rf may be a group represented by any one of the following formulae (Rf-II) to (Rf-IV): Formula (Rf-II): -(OC ３ F ６ ) d-(OC ２ F ４ )e- (wherein d is an integer of 1 to 200, and e is 0 or 1) Formula (Rf-I-II): -(OC ４ F ８ ) c-(OC ３ F ６ ) d-(OC ２ F ４ ) e-(OCF ２ )f- (wherein c and d each independently represent an integer of 0 to 30, e and f each independently represent an integer of 1 to 200, the sum of c, d, e and f is 2 or more, and the order of the repeating units assigned with c, d, e or f is arbitrary.) Formula (Rf-I-III): -(R ２０ -R ２１ ) g- (wherein, R ２０ is OCF ２ or O.C. ２ F ４ and R ２１ is O.C. ２ F ４ , O.C. ３ F ６ , O.C. ４ F ８ , O.C. ５ F １０ and O.C. ６ F １２ or a combination of two or three groups selected from these groups, and g is an integer of 2 to 100.) Formula (Rf-I-IV): -(OC ６ F １２ ) a-(OC ５ F １０ ) b-(OC ４ F ８ ) c-(OC ３ F ６ ) d-(OC ２ F４ ) e-(OCF ２ )f- (wherein e is an integer of 1 to 200, a, b, c, d and f each independently are an integer of 0 to 200, and the order of the repeating units to which a, b, c, d, e or f is assigned is arbitrary.) Formula (Rf-IV): -(OC ６ F １２ ) a-(OC ５ F １０ ) b-(OC ４ F ８ ) c-(OC ３ F ６ ) d-(OC ２ F ４ ) e-(OCF ２ )f- (wherein f is an integer of 1 to 200, a, b, c, d, and e each independently are an integer of 0 to 200, and the order of the repeating units assigned a, b, c, d, e, or f is arbitrary.)

[0041] In the above formula (Rf-II), d is preferably 5 to 200, more preferably 10 to 100, and even more preferably 15 to 50, and may be 25 to 35. The above formula (Rf-II) is preferably -(OCF ２ CF ２ CF ２ ) d- or -(OCF(CF ３ )CF ２ ) d- is a group represented by the formula:

[0042] In the above formula (Rf-I-II), e and f are each independently an integer of preferably 5 to 200, more preferably 10 to 200. The sum of c, d, e and f is preferably 5 or more, more preferably 10 or more, and may be 15 or more or 20 or more. The above formula (Rf-I-II) is preferably -(OCF ２ CF ２ CF ２ CF ２ )c-(OCF ２ CF ２ CF ２ ) d-(OCF ２ CF ２ ) e-(OCF ２ )f-, or a group represented by -(OC ２F ４ ) e-(OCF ２ )f-, and more preferably, -(OC ２ F ４ ) e-(OCF ２ )f- is a group represented by the formula:

[0043] In the above formula (Rf-I-III), R ２０ is preferably OC ２ F ４ and R ２１ is preferably OC ２ F ４ , O.C. ３ F ６ and O.C. ４ F ８ or a combination of two or three groups independently selected from these groups, more preferably OC ３ F ６ and O.C. ４ F ８ is a group selected from ２ F ４ , O.C. ３ F ６ and O.C. ４ F ８ Examples of the combination of two or three groups independently selected from the group consisting of, but not limited to, -OC ２ F ４ O.C. ３ F ６ -, -OC ２ F ４ O.C. ４ F ８ -, -OC ３ F ６ O.C. ２ F ４ -, -OC ３ F ６ O.C. ３ F ６ -, -OC ３ F ６ O.C. ４ F ８ -, -OC4F8OC ４ F ８ -, -OC ４ F ８ O.C. ３ F ６ -, -OC４ F ８ O.C. ２ F ４ -, -OC ２ F ４ OC2F4OC ３ F ６ -, -OC ２ F ４ O.C. ２ F ４ O.C. ４ F ８ -, -OC ２ F ４ O.C. ３ F ６ OC2F4-, -OC ２ F ４ O.C. ３ F ６ O.C. ３ F ６ -, -OC ２ F ４ O.C. ４ F ８ O.C. ２ F ４ -, -OC ３ F ６ O.C. ２ F ４ O.C. ２ F ４ -, -OC ３ F ６ O.C. ２ F ４ O.C. ３ F ６ -, -OC ３ F ６ OC3F6OC ２ F ４ - and -OC ４ F ８ O.C. ２ F ４ O.C. ２ F ４ In the above formula (Rf-I-III), g is preferably an integer of 3 or more, more preferably an integer of 5 or more. The above g is preferably an integer of 50 or less. In the above formula (Rf-I-III), OC ２ F ４ , O.C. ３ F ６ , O.C. ４ F ８ , O.C. ５ F１０ , and O.C. ６ F １２ may be either a straight chain or a branched chain, and is preferably a straight chain. In this embodiment, the above formula (Rf-I-III) is preferably —(OC ２ F ４ -OC ３ F ６ ) g- or -(OC ２ F ４ -OC ４ F ８ ) g-.

[0044] In the above formula (Rf-I-IV), e is preferably an integer of 1 to 100, more preferably an integer of 5 to 100. The sum of a, b, c, d, e, and f is preferably 5 or more, more preferably 10 or more, for example, 10 to 100.

[0045] In the above formula (Rf-IV), f is preferably an integer of 1 to 100, more preferably an integer of 5 to 100. The sum of a, b, c, d, e, and f is preferably 5 or more, more preferably 10 or more, for example, 10 to 100.

[0046] In Rf, the ratio of e to f (hereinafter referred to as the "e / f ratio") may be 0.5 to 4, preferably 0.6 to 3, more preferably 0.7 to 2, and even more preferably 0.8 to 1.4. By setting the e / f ratio to 4 or less, lubricity and chemical stability are further improved. The smaller the e / f ratio, the more improved the lubricity. On the other hand, by setting the e / f ratio to 0.5 or more, the stability of the compound can be further increased. The larger the e / f ratio, the more improved the stability of the fluoropolyether structure. In this case, the e / f ratio is preferably 0.8 or more.

[0047] Rf is represented by the following formula (Rf-I-VI): -(OCF ２ CF ２ CF ２ )a-(OCF(CF ３ )CF ２ ) b-(OCF ２ CF(CF3))c-(OCF ２ CF ２ )d-(OCF(CF３ ))e-(OCF ２ )f- (wherein a, b, c, d, e, and f each independently represent an integer of 0 to 200, the sum of a, b, c, d, e, and f is 1 or more, and the order of the repeating units assigned with a, b, c, d, e, or f is arbitrary).

[0048] Rf is represented by the following formula (Rf-I-VII): -(OCF ２ CF ２ )d-(OCF(CF ３ ))e-(OCF ２ )f- (wherein d, e, and f each independently represent an integer of 0 to 200, the sum of d, e, and f is 1 or more, and the order of the repeating units to which d, e, or f is added is arbitrary.) When Rf is this group, it is thought that an increase in the number of ether bonds facilitates coordination of salt cations, thereby improving salt solubility.

[0049] In Rf, the ratio of d to f (hereinafter referred to as the "d / f ratio") may be 0.5 to 4, preferably 0.6 to 3, more preferably 0.7 to 2, and even more preferably 0.8 to 1.4. By setting the d / f ratio to 4 or less, lubricity and chemical stability are further improved. The smaller the d / f ratio, the more improved the lubricity. On the other hand, by setting the d / f ratio to 0.5 or more, the stability of the compound can be further increased. The larger the d / f ratio, the more improved the stability of the fluoropolyether structure. In this case, the d / f ratio is preferably 0.8 or more.

[0050] Each Rf is preferably independently a group represented by the above formula (Rf-II) or (Rf-I-II), and more preferably a group represented by the above formula (Rf-I-II).

[0051] The number average molecular weight of Rf is not particularly limited, but is, for example, 500 to 30,000, preferably 1,500 to 30,000, and more preferably 2,000 to 10,000. １９ This is a value measured by F-NMR.

[0052] R １ ~R ３ The alkyl group and fluoroalkyl group of R may be linear or branched, but are preferably linear. １ ~R ３ Examples of the aryl group include a phenyl group, a 4-nitrophenyl group, a 4-acetylaminophenyl group, and a 4-methanesulfonylphenyl group.

[0053] R １ ~R ３ are each independently preferably an alkyl group having 1 to 3 carbon atoms or a fluoroalkyl group having 1 to 3 carbon atoms, more preferably a methyl group, an ethyl group, a trifluoromethyl group or a pentafluoroethyl group, and even more preferably a methyl group, a trifluoromethyl group or a pentafluoroethyl group.

[0054] The fluoropolyether is particularly preferably the fluoropolyether represented by the formula (1) above, since it has sufficient ionic conductivity and an effect of improving high-temperature durability.

[0055] The fluoropolyether is preferably a liquid at any temperature between 25°C and 80°C, and more preferably a liquid at 25°C, because it has sufficient ionic conductivity and a good effect of improving high-temperature durability. Examples of a form "liquid at any temperature between 25°C and 80°C" include a form that is solid at 25°C and liquid at 50°C, and a form that is solid at 50°C and liquid at 80°C. A form that is liquid at low temperatures and solid at high temperatures does not normally exist, and therefore is not included in the form "liquid at any temperature between 25°C and 80°C".

[0056] In the composition of the present disclosure, the content of the fluoropolyether is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more. The upper limit is not particularly limited, but is usually 99.9% by mass or less, preferably 99.5% by mass or less, and more preferably 98.5% by mass or less.

[0057] As the salt, it is preferable to use any electrolyte salt that can be used in various types of battery electrolytes, such as lithium salt, sodium salt, ammonium salt, metal salt, liquid salt (ionic liquid), inorganic polymer salt, organic polymer salt, etc.

[0058] Examples of batteries that use the composition of the present disclosure as an electrolyte include lithium ion batteries, sodium ion batteries, magnesium ion batteries, calcium ion batteries, and fluoride ion batteries, with lithium ion batteries being preferred.

[0059] When the composition of the present disclosure is used as an electrolyte for a lithium ion battery, the electrolyte salt is preferably a lithium salt. Any lithium salt can be used as the lithium salt, and specific examples thereof include the following: ６ , LiBF ４ , LiClO ４ , LiAlF ４ , LiSbF ６ , LiTaF ６ , LiWF ７ , LiAsF ６ , LiAlCl ４ , LiI, LiBr, LiCl, LiB １０ Cl １０ , Li ２ SiF ６ , Li ２ PFO ３ , LiPO ２ F ２ Inorganic lithium salts such as LiWOF ５ Lithium tungstates such as HCO ２ Li, C.H. ３ CO ２ Li, C.H. ２ FCO ２ Li, CHF ２ CO ２ Li, CF ３ CO ２ Li, CF ３ CH ２ CO ２ Li, CF ３ CF ２ CO ２ Li, CF ３ CF ２ CF ２CO ２ Li, CF ３ CF ２ CF ２ CF ２ CO ２ Lithium carboxylate salts such as Li; FSO ３ Li, C.H. ３ SO ３ Li, C.H. ２ FSO ３ Li, CHF ２ SO ３ Li, CF ３ SO ３ Li, CF ３ CF ２ SO ３ Li, CF ３ CF ２ CF ２ SO ３ Li, CF ３ CF ２ CF ２ CF ２ SO ３ Li, lithium methyl sulfate, lithium ethyl sulfate (C ２ H ５ OSO ３ Lithium salts having an S═O group, such as lithium bis(trifluoromethanesulfonimide) (LiTFSI), lithium bis(monofluorosulfonimide) (LiFSI), and LiN(FCO). ２ , LiN(FCO)(FSO ２ ), LiN(FSO ２ ) ２ , LiN(FSO ２ ) (CF ３ SO ２ ), LiN(CF ３ SO ２ ) ２ , LiN(C ２ F ５ SO ２ ) ２, lithium bisperfluoroethanesulfonylimide, lithium cyclic 1,2-perfluoroethanedisulfonylimide, lithium cyclic 1,3-perfluoropropanedisulfonylimide, lithium cyclic 1,2-ethanedisulfonylimide, lithium cyclic 1,3-propanedisulfonylimide, lithium cyclic 1,4-perfluorobutanedisulfonylimide, LiN(CF ３ SO ２ ) (FSO ２ ), LiN(CF ３ SO ２ ) (C ３ F ７ SO ２ ), LiN(CF ３ SO ２ ) (C ４ F ９ SO ２ ), LiN (POF ２ ) ２ Lithium imide salts such as LiC(FSO ２ ) ３ , LiC(CF ３ SO ２ ) ３ , LiC(C ２ F ５ SO ２ ) ３ Lithium methide salts such as: ａ (C ｎ F ２ｎ＋１ ) ６－ａ (wherein a is an integer of 0 to 5, and n is an integer of 1 to 6) ３ (C ２ F ５ ) ３ , LiPF ３ (CF ３ ) ３ , LiPF ３ (iso-C ３ F ７ ) ３ , LiPF ５ (iso-C ３ F ７ ), LiPF ４ (CF ３ ) ２ , LiPF ４ (C ２ F５ ) ２ ), LiPF ４ (CF ３ SO ２ ) ２ , LiPF ４ (C ２ F ５ SO ２ ) ２ , LiBF ３ CF ３ , LiBF ３ C ２ F ５ , LiBF ３ C ３ F ７ , LiBF ２ (CF ３ ) ２ , LiBF ２ (C ２ F ５ ) ２ , LiBF ２ (CF ３ SO ２ ) ２ , LiBF ２ (C ２ F ５ SO ２ ) ２ Fluorine-containing organic lithium salts such as LiSCN and LiB(CN) ４ , LiB(C ６ H ５ ) ４ , Li ２ (C ２ O ４ ), LiP(C ２ O ４ ) ３ , Li ２ B １２ F ｂ H １２－ｂ (b is an integer of 0 to 3), etc.

[0060] Among them, LiTFSI, LiFSI, LiPF ６ , LiBF ４ , LiSbF ６ , LiTaF ６ , LiPO ２ F ２ , FSO ３ Li, CF ３ SO ３Li, LiN (FSO ２ ) ２ , LiN(FSO ２ ) (CF ３ SO ２ ), LiN(CF ３ SO ２ ) ２ , LiN(C ２ F ５ SO ２ ) ２ , lithium cyclic 1,2-perfluoroethane disulfonylimide, lithium cyclic 1,3-perfluoropropane disulfonylimide, LiC(FSO ２ ) ３ , LiC(CF ３ SO ２ ) ３ , LiC(C ２ F ５ SO ２ ) ３ , LiBF ３ CF ３ , LiBF ３ C ２ F ５ , LiPF ３ (CF ３ ) ３ , LiPF ３ (C ２ F ５ ) ３ and the like are preferred, and LiTFSI, LiFSI, LiPF ６ is particularly preferred.

[0061] These lithium salts may be used alone or in combination of two or more. A preferred example of a combination of two or more is LiPF ６ and LiTFSI in combination, or LiTFSI and LiPO ２ F ２ , LiBF ４ or FSO ３ When used in combination with Li, it has the effect of improving high-temperature storage characteristics, load characteristics, and cycle characteristics.

[0062] Another example is the combined use of an inorganic lithium salt and an organic lithium salt, which has the effect of suppressing deterioration due to high-temperature storage. ３ SO ３Li, LiN (FSO ２ ) ２ , LiN(FSO ２ ) (CF ３ SO ２ ), LiN(CF ３ SO ２ ) ２ , LiN(C ２ F ５ SO ２ ) ２ , lithium cyclic 1,2-perfluoroethane disulfonylimide, lithium cyclic 1,3-perfluoropropane disulfonylimide, LiC(FSO ２ ) ３ , LiC(CF ３ SO ２ ) ３ , LiC(C ２ F ５ SO ２ ) ３ , LiBF ３ CF ３ , LiBF ３ C ２ F ５ , LiPF ３ (CF ３ ) ３ , LiPF ３ (C ２ F ５ ) ３ etc. are preferred.

[0063] When the composition of the present disclosure is used as an electrolyte for a fluoride ion battery, the electrolyte salt is preferably a fluoride salt.

[0064] The fluoride salt is not particularly limited as long as it generates fluoride ions, and may be an organic fluoride salt or an inorganic fluoride salt. The fluoride salt may also be an ionic liquid. More specifically, ammonium fluoride, metal fluorides, etc. may be used. These may be used alone or in combination of two or more. Ammonium fluoride is preferred because of its good solubility.

[0065] Specific examples of the metal fluorides include alkali or alkaline earth fluorides (e.g., LiF, CsF, MgF ２ , BaF２ ), transition metal fluorides (e.g., VF ４ , FeF ３ , MoF ６ , PdF ２ , AgF), main group metal fluorides (e.g., AlF ３ , PbF ４ , BiF ３ ), lanthanide or actinide fluorides (e.g., LaF ３ , YbF ３ , U.F. ５ ) are listed.

[0066] Examples of the ammonium fluoride include ammonium hydrogen fluoride, alkyl ammonium fluoride, etc. Alkyl ammonium fluoride is preferred because of its good solubility.

[0067] The alkylammonium fluoride is N ＋ -Rx ４ Preferably, Rx has a cation represented by the formula: Each Rx is independently an alkyl group or a fluoroalkyl group, and preferably an alkyl group. The number of carbon atoms in Rx is, for example, 1 to 10, and may be 5 or less, or 3 or less.

[0068] The alkyl group and fluoroalkyl group in the alkylammonium fluoride may be linear or branched, but preferably at least one is branched, and more preferably both branched and linear. The number of carbon atoms in the alkyl group and fluoroalkyl group is preferably 1 or more, and preferably 10 or less, more preferably 8 or less, and even more preferably 6 or less. The number of carbon atoms in the linear alkyl group and linear fluoroalkyl group is preferably 1 or more, and preferably 10 or less, more preferably 5 or less, and even more preferably 3 or less. The number of carbon atoms in the branched alkyl group and branched fluoroalkyl group is preferably 1 or more, more preferably 3 or more, and even more preferably 4 or more, and preferably 10 or less, more preferably 8 or less, and even more preferably 6 or less.

[0069] In the composition of the present disclosure, the content of the above salt is preferably 0.1% by mass or more, more preferably 1% by mass or more, and is preferably 30% by mass or less, more preferably 20% by mass or less.

[0070] In the composition of the present disclosure, the content of the polyalkylene oxide represented by the following formula (5) is preferably less than 20 mass %, which improves the chemical stability, typified by the oxidation resistance, of the composition. １Ｂ -(OCHR １Ａ (CH ２ ) jCHR ２Ａ ) n-OR ２Ｂ (In the formula, R １Ａ and R ２Ａ are each independently a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, j is an integer of 0 or 1 or 2, and R １Ｂ and R ２Ｂ are each independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and n is an integer of 5 to 1000.

[0071] In the composition of the present disclosure, the content of the polyalkylene oxide represented by the above formula (5) is more preferably 10% by mass or less, even more preferably 5% by mass or less, and particularly preferably 1% by mass or less. The lower limit is not particularly limited, and may be 0% by mass.

[0072] <Electrolyte> The composition of the present disclosure is useful as an electrolyte because it can improve the high-temperature durability of electrochemical devices. The present disclosure also relates to an electrolyte comprising the composition of the present disclosure.

[0073] In the electrolyte solution of the present disclosure, the suitable ranges of the content of the fluoropolyether and the content of the salt are the same as those explained for the composition of the present disclosure.

[0074] In the electrolytic solution of the present disclosure, the fluoropolyether is usually used as a solvent. The content of the fluoropolyether relative to the solvent is preferably 70% by volume or more, more preferably 80% by volume or more, and even more preferably 90% by volume or more. The upper limit is not particularly limited, and may be 100% by mass.

[0075] The electrolyte solution of the present disclosure may use a solvent other than the fluoropolyether. Examples of solvents other than the fluoropolyether include conventionally known solvents for non-aqueous secondary batteries, such as carbonate-based solvents, ester-based solvents, ether-based solvents, and fluorobenzene-based solvents. Examples of carbonate-based solvents include cyclic carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate, and fluoroethylene carbonate, and linear carbonates such as dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate. Examples of ester-based solvents include cyclic esters such as γ-butyrolactone and γ-valerolactone, and linear esters such as methyl acetate and ethyl acetate. Examples of ether-based solvents include cyclic ethers such as tetrahydrofuran and 2-methyltetrahydrofuran, and linear ethers such as dimethoxyethane and glyme-based compounds. Examples of glyme-based compounds include diethylene glycol diethyl ether, triethylene glycol dimethyl ether, and tetraethylene glycol dimethyl ether. Examples of fluorobenzene-based solvents include 1,3-difluorobenzene, 1,2,4-trifluorobenzene, and 1,2,3,4-tetrafluorobenzene. These may be used alone or in combination of two or more. In the present disclosure, ether-based solvents are preferred, chain ethers are more preferred, and glyme-based compounds are even more preferred. Furthermore, the compounds described herein may be used in small amounts as additives.

[0076] The ionic conductivity of the electrolyte solution of the present disclosure is preferably 1.0×10 －７ S / cm or more, more preferably 1.0×10 －６ S / cm or more, more preferably 1.0×10 －５ The upper limit is not particularly limited, but is preferably 1.0 × 10 －３ The ionic conductivity is a value obtained by measurement at 25°C using a SevenCompact S230 manufactured by Mettler Toledo.

[0077] The Li ion transport number of the electrolyte solution of the present disclosure is preferably 0.2 or more, more preferably 0.25 or more, and even more preferably 0.3 or more. There is no particular upper limit, but it is preferably 0.5 or less. The Li ion transport number is a value determined by the following method (pulsed magnetic field gradient NMR measurement). The pulsed magnetic field gradient NMR measurement is performed at 25°C using a JEOL JNM-ECA400WB. ７ The self-diffusion coefficient D is [In the formula, A(0) is the peak intensity when no magnetic field gradient pulse is applied, A(g) is the peak intensity at each gradient magnetic field intensity g, δ is the magnetic field gradient pulse width, Δ is the diffusion time (100 ms) of the molecule being observed, γ is the gyromagnetic ratio, and D is the diffusion coefficient.] By plotting the left side of the formula on the vertical axis and k on the horizontal axis, the diffusion coefficient D can be obtained from the slope of the approximate line.

[0078] Polymer Electrolyte The present disclosure also relates to a polymer electrolyte comprising the electrolyte solution of the present disclosure.

[0079] The polymer electrolyte of the present disclosure includes, for example, a gel electrolyte in which a polymer material is plasticized with the electrolytic solution of the present disclosure.

[0080] Examples of the polymer material include conventionally known polyethylene oxide, polypropylene oxide, and modified products thereof (see JP-A-8-222270 and JP-A-2002-100405); polyacrylate polymers, polyacrylonitrile, fluororesins such as polyvinylidene fluoride and vinylidene fluoride-hexafluoropropylene copolymers (see JP-A-4-506726, JP-A-8-507407, and JP-A-10-294131); and composites of these fluororesins with hydrocarbon resins (see JP-A-11-35765 and JP-A-11-86630). Polyvinylidene fluoride and vinylidene fluoride-hexafluoropropylene copolymers are particularly preferred.

[0081] <Electrochemical Device> The present disclosure also relates to an electrochemical device comprising the electrolyte solution of the present disclosure or the polymer electrolyte of the present disclosure.

[0082] The electrochemical device of the present disclosure preferably comprises a positive electrode, a negative electrode, etc., and more specifically, is preferably a secondary battery comprising these, and particularly preferably a lithium ion secondary battery.

[0083] The positive electrode active material used in the positive electrode is not particularly limited as long as it can electrochemically absorb and release alkali metal ions, but for example, a material containing an alkali metal and at least one transition metal is preferred. Specific examples include alkali metal-containing transition metal complex oxides and alkali metal-containing transition metal phosphate compounds. Of these, alkali metal-containing transition metal complex oxides that generate high voltage are particularly preferred as the positive electrode active material. Examples of the alkali metal ions include lithium ions, sodium ions, and potassium ions, with lithium ions being preferred.

[0084] Examples of the alkali metal-containing transition metal composite oxide include those represented by the formula: M ａ Mn ２－ｂ M １ ｂ O ４ (Wherein, M is at least one metal selected from the group consisting of Li, Na, and K; 0.9≦a; 0≦b≦1.5; M １ and Mn is at least one metal selected from the group consisting of Fe, Co, Ni, Cu, Zn, Al, Sn, Cr, V, Ti, Mg, Ca, Sr, B, Ga, In, Si, and Ge), a lithium-manganese spinel composite oxide represented by the formula: MNi １－ｃ M ２ ｃ O ２ (Wherein, M is at least one metal selected from the group consisting of Li, Na, and K; 0≦c≦0.5; M ２ is at least one metal selected from the group consisting of Fe, Co, Mn, Cu, Zn, Al, Sn, Cr, V, Ti, Mg, Ca, Sr, B, Ga, In, Si, and Ge), or a lithium-nickel composite oxide represented by the formula: MCo １－ｄ M ３ ｄ O ２ (Wherein, M is at least one metal selected from the group consisting of Li, Na, and K; 0≦d≦0.5; M３ and M is at least one metal selected from the group consisting of Fe, Ni, Mn, Cu, Zn, Al, Sn, Cr, V, Ti, Mg, Ca, Sr, B, Ga, In, Si, and Ge. In the above, M is preferably one metal selected from the group consisting of Li, Na, and K, more preferably Li or Na, and even more preferably Li.

[0085] Among these, MCoO is preferred because it can provide a secondary battery with high energy density and high output. ２ , M MnO ２ , MNiO ２ , M.M. ２ O ４ , MNi ０．８ Co ０．１５ Al ０．０５ O ２ , or MNi １／３ Co １／３ Mn １／３ O ２ and the like are preferred, and a compound represented by the following general formula is preferred: MNi ｈ Co ｉ Mn ｊ M ５ ｋ O ２ (wherein M is at least one metal selected from the group consisting of Li, Na, and K, and M ５ represents at least one selected from the group consisting of Fe, Cu, Zn, Al, Sn, Cr, V, Ti, Mg, Ca, Sr, B, Ga, In, Si, and Ge, and (h+i+j+k)=1.0, 0≦h≦1.0, 0≦i≦1.0, 0≦j≦1.5, 0≦k≦0.2.

[0086] Examples of the alkali metal-containing transition metal phosphate compound include those represented by the following general formula: ｅ M ４ ｆ (P.O. ４ ) ｇ (wherein M is at least one metal selected from the group consisting of Li, Na, and K, and M ４represents at least one selected from the group consisting of V, Ti, Cr, Mn, Fe, Co, Ni, and Cu, and 0.5≦e≦3, 1≦f≦2, and 1≦g≦3. In the above, M is preferably one metal selected from the group consisting of Li, Na, and K, more preferably Li or Na, and even more preferably Li.

[0087] The transition metal in the alkali metal-containing transition metal phosphate compound is preferably V, Ti, Cr, Mn, Fe, Co, Ni, Cu, or the like, and specific examples thereof include LiFePO ４ , Li ３ Fe ２ (P.O. ４ ) ３ , LiFeP ２ O ７ Iron phosphates such as LiCoPO ４ and lithium transition metal phosphate compounds in which a part of the transition metal atoms constituting the main component of these compounds is substituted with other elements such as Al, Ti, V, Cr, Mn, Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Nb, Si, etc. The lithium-containing transition metal phosphate compounds preferably have an olivine structure.

[0088] Other examples of the positive electrode active material include lithium-nickel-based composite oxides. The lithium-nickel-based composite oxides are represented by the following general formula: Li ｙ Ni １－ｘ M ｘ O ２ (wherein x is 0.01≦x≦0.7, y is 0.9≦y≦2.0, and M is a metal atom (excluding Li and Ni)) is preferred.

[0089] Other positive electrode active materials include MFePO ４ , MNi ０．８ Co ０．２ O ２ , M １．２ Fe ０．４ Mn ０．４ O ２ , MNi ０．５ Mn １．５ O ２ , M.V.３ O ６ , M ２ MnO ３ In particular, M ２ MnO ３ , MNi ０．５ Mn １．５ O ２ These positive electrode active materials are preferred in that their crystalline structure does not collapse even when the secondary battery is operated at a voltage exceeding 4.4 V or a voltage of 4.6 V or higher. Therefore, electrochemical devices such as secondary batteries using positive electrode materials containing the above-mentioned positive electrode active materials are preferred because they are less likely to reduce their remaining capacity and change their resistance increase rate even when stored at high temperatures, and their battery performance does not deteriorate even when operated at high voltages.

[0090] Other positive electrode active materials include M ２ MnO ３ and M.M. ６ O ２ (wherein M is at least one metal selected from the group consisting of Li, Na, and K, and M ６ Examples of the material include solid solution materials with transition metals such as Co, Ni, Mn, and Fe.

[0091] The solid solution material may be, for example, a material represented by the general formula M ｘ [Mn （１－ｙ） M ７ ｙ ]O ｚ In the formula, M is at least one metal selected from the group consisting of Li, Na, and K, and M ７ is composed of at least one metal element other than M and Mn, and contains, for example, one or more elements selected from the group consisting of Co, Ni, Fe, Ti, Mo, W, Cr, Zr and Sn. The values ​​of x, y and z in the formula are in the ranges of 1<x<2, 0≦y<1 and 1.5<z<3. Among them, Li １．２ Mn ０．５ Co ０．１４ Ni ０．１４ O ２ Li like ２ MnO ３ Based on LiNiO ２ and LiCoO ２A manganese-containing solid solution material containing manganese is preferred in that it can provide an alkali metal ion secondary battery having a high energy density.

[0092] Furthermore, it is preferable to include lithium phosphate in the positive electrode active material, since this improves continuous charging characteristics. Although there is no limitation on the use of lithium phosphate, it is preferable to use a mixture of the positive electrode active material and lithium phosphate. The amount of lithium phosphate used, based on the total amount of the positive electrode active material and lithium phosphate, is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and even more preferably 0.5% by mass or more, and is preferably 10% by mass or less, more preferably 8% by mass or less, and even more preferably 5% by mass or less.

[0093] Alternatively, a substance having a different composition may be attached to the surface of the positive electrode active material, such as an oxide, such as aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, magnesium oxide, calcium oxide, boron oxide, antimony oxide, or bismuth oxide; a sulfate, such as lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, calcium sulfate, or aluminum sulfate; a carbonate, such as lithium carbonate, calcium carbonate, or magnesium carbonate; or carbon.

[0094] The surface-attaching substance can be attached to the surface of the positive electrode active material by, for example, a method of dissolving or suspending the substance in a solvent, impregnating the positive electrode active material, and then drying, a method of dissolving or suspending a surface-attaching substance precursor in a solvent, impregnating the positive electrode active material, and then reacting the surface-attaching substance by heating, or a method of adding the surface-attaching substance to a positive electrode active material precursor and simultaneously calcining the surface-attaching substance, etc. When carbon is attached, a method of mechanically attaching the carbonaceous material in the form of, for example, activated carbon, can also be used.

[0095] The amount of the surface-attached substance is preferably 0.1 ppm or more, more preferably 1 ppm or more, and even more preferably 10 ppm or more by mass relative to the positive electrode active material, and is preferably 20% or less, more preferably 10% or less, and even more preferably 5% or less by mass relative to the positive electrode active material. The surface-attached substance can suppress the oxidation reaction of the electrolyte on the surface of the positive electrode active material and improve the battery life, but if the amount of attachment is too small, the effect will not be fully exerted, and if it is too large, the movement of lithium ions into and out of the positive electrode active material will be hindered, which may increase the resistance.

[0096] The shape of the particles of the positive electrode active material may be any of the conventional shapes, such as block, polyhedron, sphere, oval sphere, plate, needle, column, etc. Primary particles may also be aggregated to form secondary particles.

[0097] The tap density of the positive electrode active material is preferably 0.5 g / cm ３ More preferably, 0.8 g / cm ３ More preferably, 1.0 g / cm ３ That is all. If the tap density of the positive electrode active material is below the above lower limit, the amount of dispersion medium required when forming the positive electrode active material layer increases, and the amounts of conductive material and binder required also increase, which may restrict the filling rate of the positive electrode active material in the positive electrode active material layer and restrict the battery capacity. By using a composite oxide powder with a high tap density, a high-density positive electrode active material layer can be formed. Generally, the higher the tap density, the more preferable it is, and there is no particular upper limit. However, if the tap density is too high, the diffusion of lithium ions in the positive electrode active material layer using the electrolyte as a medium becomes rate-limiting, and the load characteristics may be easily reduced. Therefore, the upper limit is preferably 4.0 g / cm. ３ or less, more preferably 3.7 g / cm ３ More preferably 3.5 g / cm or less ３ The tap density is the powder packing density (tap density) g / cm when 5 to 10 g of the positive electrode active material powder is placed in a 10 ml glass measuring cylinder and tapped 200 times with a stroke of about 20 mm. ３ is required.

[0098] The median diameter d50 of the particles of the positive electrode active material (the secondary particle diameter when primary particles are aggregated to form secondary particles) is preferably 0.3 μm or more, more preferably 0.5 μm or more, even more preferably 0.8 μm or more, and most preferably 1.0 μm or more, and is preferably 30 μm or less, more preferably 27 μm or less, even more preferably 25 μm or less, and most preferably 22 μm or less. If the diameter is below the lower limit, a high tap density product may not be obtained, and if the diameter is above the upper limit, it may take a long time for lithium to diffuse within the particles, resulting in problems such as a decrease in battery performance. Here, by mixing two or more types of the positive electrode active material having different median diameters d50, the filling property during positive electrode production can be further improved.

[0099] The median diameter d50 is measured using a known laser diffraction / scattering particle size distribution analyzer. When using a HORIBA LA-920 particle size distribution analyzer, the measurement is performed using a 0.1% by mass aqueous solution of sodium hexametaphosphate as the dispersion medium, and after ultrasonic dispersion for 5 minutes, the measurement is performed with a refractive index set to 1.24.

[0100] When primary particles aggregate to form secondary particles, the average primary particle diameter of the positive electrode active material is preferably 0.05 μm or more, more preferably 0.1 μm or more, and even more preferably 0.2 μm or more. The upper limit is preferably 5 μm or less, more preferably 4 μm or less, even more preferably 3 μm or less, and most preferably 2 μm or less. If the upper limit is exceeded, it is difficult to form spherical secondary particles, which may adversely affect powder packing and significantly reduce the specific surface area, thereby increasing the possibility of battery performance, such as output characteristics, being degraded. Conversely, if the lower limit is exceeded, problems such as poor charge / discharge reversibility may occur due to underdeveloped crystals. The average primary particle diameter is measured by observation using a scanning electron microscope (SEM). Specifically, in a photograph at 10,000x magnification, the longest intercepts of the horizontal line at the left and right boundaries of the primary particles are determined for any 50 primary particles, and the average is calculated.

[0101] The BET specific surface area of ​​the positive electrode active material is preferably 0.1 m ２ / g or more, more preferably 0.2m ２ / g or more, more preferably 0.3m ２ / g or more, and the upper limit is preferably 50m ２ / g or less, more preferably 40m ２ / g or less, more preferably 30m ２ / g or less. If the BET specific surface area is smaller than this range, battery performance is likely to decrease, while if it is larger, it is difficult to increase the tap density, which may lead to problems with processability when forming the positive electrode active material layer. The BET specific surface area is defined as a value measured by a nitrogen adsorption BET single-point method using a surface area meter (e.g., a fully automatic surface area measuring device manufactured by Ohkura Riken Co., Ltd.) after pre-drying a sample at 150°C for 30 minutes under a nitrogen flow, using a nitrogen-helium mixed gas accurately adjusted so that the relative pressure of nitrogen to atmospheric pressure is 0.3.

[0102] When used in large-scale lithium-ion secondary batteries for hybrid vehicles or distributed power sources, high output is required, so it is preferable that the particles of the positive electrode active material are mainly secondary particles. The particles of the positive electrode active material preferably have an average secondary particle size of 40 μm or less and contain 0.5 to 7.0 volume % of fine particles having an average primary particle size of 1 μm or less. The inclusion of fine particles having an average primary particle size of 1 μm or less increases the contact area with the electrolyte, allowing for faster diffusion of lithium ions between the electrode mixture and the electrolyte, thereby improving the output performance of the battery.

[0103] As a method for producing the positive electrode active material, a general method for producing an inorganic compound is used. In particular, various methods can be considered for producing a spherical or oval-spherical active material. For example, a raw material of a transition metal is dissolved or pulverized and dispersed in a solvent such as water, and the pH is adjusted while stirring to produce and recover a spherical precursor. This is then dried as necessary, and then the precursor is dissolved in LiOH, Li ２ CO ３ , LiNO ３ and baking at a high temperature to obtain an active material.

[0104] The positive electrode active material may be used alone or in any combination or ratio of two or more different types of materials. ２ and LiNi ０．３３ Co ０．３３ Mn ０．３３ O ２ combination with ternary systems such as LiCoO ２ and LiMn ２ O ４ Or a combination of this with a material in which a part of Mn is replaced with another transition metal, or LiFePO ４ and LiCoO ２ Alternatively, a combination of Co with other transition metals or the like may be used.

[0105] The content of the positive electrode active material is preferably 50 to 99.5% by mass of the electrode mixture, more preferably 80 to 99% by mass, in terms of high battery capacity. The content in the positive electrode active material layer is preferably 80% by mass or more, more preferably 82% by mass or more, and particularly preferably 84% by mass or more. The upper limit is preferably 99% by mass or less, more preferably 98% by mass or less. If the content of the positive electrode active material in the positive electrode active material layer is low, the electrical capacity may be insufficient. Conversely, if the content is too high, the strength of the positive electrode may be insufficient.

[0106] The negative electrode active material used in the negative electrode is not particularly limited, and examples thereof include carbonaceous materials such as lithium metal, artificial graphite, graphite carbon fiber, resin-baked carbon, pyrolytic vapor-grown carbon, coke, mesocarbon microbeads (MCMB), furfuryl alcohol resin-baked carbon, polyacene, pitch-based carbon fiber, vapor-grown carbon fiber, natural graphite, and non-graphitizable carbon; silicon-containing compounds such as silicon and silicon alloys; Li ４ Ti ５ O １２ Among these, those containing at least a carbonaceous material and silicon-containing compounds are particularly suitable.

[0107] The negative electrode active material preferably contains silicon as a constituent element, which allows the production of a high-capacity battery.

[0108] The silicon-containing material includes silicon particles, particles having a structure in which silicon particles are dispersed in a silicon-based compound, and silicon-based particles having the general formula SiO ｘ (0.5≦x≦1.6), or a mixture thereof. By using these, a negative electrode mixture for a lithium ion secondary battery having higher initial charge / discharge efficiency, high capacity, and excellent cycle characteristics can be obtained.

[0109] Silicon oxide in the present disclosure is a general term for amorphous silicon oxide, and silicon oxide before disproportionation has the general formula SiO ｘ (0.5≦x≦1.6). Preferably, x satisfies 0.8≦x<1.6, and more preferably 0.8≦x<1.3. This silicon oxide can be obtained, for example, by heating a mixture of silicon dioxide and metallic silicon to produce silicon monoxide gas, which is then cooled and precipitated.

[0110] Particles having a structure in which silicon particles are dispersed in a silicon-based compound can be prepared by, for example, a method of baking a mixture of silicon particles and a silicon-based compound, or by a method using a compound of the general formula SiO ｘ The silicon oxide particles before disproportionation, represented by the formula (I), are heat-treated in an inert, non-oxidizing atmosphere such as argon at a temperature of 400°C or higher, preferably 800 to 1,100°C, to carry out a disproportionation reaction. The material obtained by the latter method is particularly suitable because the silicon crystallites are uniformly dispersed. The disproportionation reaction described above allows the silicon nanoparticles to have a size of 1 to 100 nm. The silicon oxide in the particles having a structure in which silicon nanoparticles are dispersed in silicon oxide is preferably silicon dioxide. The dispersion of silicon nanoparticles (crystals) in amorphous silicon oxide can be confirmed using a transmission electron microscope.

[0111] The physical properties of the silicon-containing particles can be appropriately selected depending on the target composite particles. For example, the average particle size is preferably 0.1 to 50 μm, with the lower limit being more preferably 0.2 μm or more, and even more preferably 0.5 μm or more. The upper limit is more preferably 30 μm or less, and even more preferably 20 μm or less. The average particle size is expressed as the weight-average particle size in particle size distribution measurement by laser diffraction method. The BET specific surface area is 0.5 to 100 m ２ / g is preferred, and 1 to 20m ２ / g is more preferable. ２ If the porosity is 100 m / g or more, there is no risk of the adhesiveness being reduced when the electrode is coated with the porosity being reduced, resulting in a deterioration in battery characteristics. ２ / g or less, the proportion of silicon dioxide on the particle surface is large, and there is no risk of a decrease in battery capacity when used as a negative electrode material for a lithium ion secondary battery.

[0112] The silicon-containing particles are coated with carbon to impart conductivity, thereby improving battery performance. Methods for imparting conductivity include mixing with conductive particles such as graphite, coating the surfaces of the silicon-containing particles with a carbon coating, and combining both methods. The carbon coating method is preferred, and chemical vapor deposition (CVD) is more preferred.

[0113] In order to increase the capacity of the resulting electrode mixture, the content of the negative electrode active material is preferably 40% by mass or more, more preferably 50% by mass or more, and particularly preferably 60% by mass or more, of the electrode mixture, and the upper limit is preferably 99% by mass or less, more preferably 98% by mass or less.

[0114] The electrode mixture constituting the positive electrode or the negative electrode may contain a conductive aid. The conductive aid is not particularly limited, but examples thereof include metal materials such as copper, nickel, and gold, graphite such as natural graphite and artificial graphite, carbon black such as acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black, and carbon materials such as needle coke, carbon nanotubes, fullerenes, and amorphous carbon such as VGCF. These may be used alone or in any combination and ratio of two or more.

[0115] The conductive additive is used in an amount of usually 0.01% by mass or more, preferably 0.1% by mass or more, more preferably 1% by mass or more in the electrode mixture, and usually 50% by mass or less, preferably 30% by mass or less, more preferably 15% by mass or less.

[0116] The electrode mixture may contain a thickener. Examples of the thickener include carboxymethyl cellulose, methyl cellulose, hydroxymethyl cellulose, ethyl cellulose, polyvinyl alcohol, oxidized starch, phosphated starch, casein, polyvinylpyrrolidone, and salts thereof. One type may be used alone, or two or more types may be used in any combination and ratio.

[0117] The thickener is used in an amount of usually 0.1% by mass or more, preferably 0.2% by mass or more, more preferably 0.3% by mass or more, relative to the electrode active material, and usually 5% by mass or less, preferably 3% by mass or less, more preferably 2% by mass or less.

[0118] The electrode mixture may contain a binder. The binder is not particularly limited, and examples thereof include resin-based polymers such as polyethylene, polypropylene, polyethylene terephthalate, polymethyl methacrylate, aromatic polyamide, chitosan, alginic acid, polyacrylic acid, polyimide, cellulose, and nitrocellulose; rubber-like polymers such as SBR (styrene-butadiene rubber), isoprene rubber, butadiene rubber, fluororubber, NBR (acrylonitrile-butadiene rubber), and ethylene-propylene rubber; styrene-butadiene-styrene block copolymers or hydrogenated products thereof; and EPDM (ethylene-propylene-diene terpolymer). Examples of suitable polymers include thermoplastic elastomeric polymers such as styrene-ethylene-butadiene-styrene copolymers, styrene-isoprene-styrene block copolymers, and hydrogenated products thereof; soft resinous polymers such as syndiotactic-1,2-polybutadiene, polyvinyl acetate, ethylene-vinyl acetate copolymers, and propylene-α-olefin copolymers; fluorine-containing polymers such as polyvinylidene fluoride, vinylidene fluoride copolymers, polytetrafluoroethylene, and tetrafluoroethylene-ethylene copolymers; and polymer compositions having ionic conductivity for alkali metal ions (particularly lithium ions). These may be used alone or in any combination and ratio of two or more.

[0119] The binder is used in an amount of usually 0.1% by mass or more, preferably 0.5% by mass or more, more preferably 0.6% by mass or more, and usually 20% by mass or less, preferably 15% by mass or less, more preferably 10% by mass or less, and even more preferably 8% by mass or less, based on the electrode active material.

[0120] The positive electrode is preferably composed of a current collector and an electrode mixture sheet containing the positive electrode active material. Examples of materials for the positive electrode current collector include metals such as aluminum, titanium, tantalum, stainless steel, and nickel, or alloys thereof; and carbon materials such as carbon cloth and carbon paper. Among these, metal materials, particularly aluminum or its alloys, are preferred.

[0121] Examples of the shape of the current collector include metal foil, metal cylinder, metal coil, metal plate, expanded metal, punched metal, and foam metal in the case of a metal material, and carbon plate, carbon thin film, and carbon cylinder in the case of a carbon material. Of these, metal foil is preferred. The metal foil may be appropriately formed into a mesh shape. The thickness of the metal foil is optional, but is usually 1 μm or more, preferably 3 μm or more, and more preferably 5 μm or more, and is usually 1 mm or less, preferably 100 μm or less, and more preferably 50 μm or less. If the metal foil is thinner than this range, the strength required as a current collector may be insufficient. Conversely, if the metal foil is thicker than this range, handling may be impaired.

[0122] In addition, it is also preferable that the surface of the current collector is coated with a conductive additive, from the viewpoint of reducing the electrical contact resistance between the current collector and the positive electrode active material layer. Examples of the conductive additive include carbon and precious metals such as gold, platinum, and silver.

[0123] The positive electrode may be manufactured by a conventional method, for example, by laminating an electrode mixture sheet and a current collector with an adhesive therebetween, followed by vacuum drying.

[0124] The density of the positive electrode mixture sheet is preferably 2.50 g / cm ３ More preferably, 2.80 g / cm ３ More preferably, 3.00 g / cm ３ or more, and preferably 3.80 g / cm ３ or less, more preferably 3.70 g / cm ３ More preferably, 3.60 g / cm or less ３ The range is as follows. If the temperature exceeds this range, the permeability of the electrolyte to the vicinity of the current collector / active material interface will decrease, and the charge / discharge characteristics, especially at high current densities, will decrease, and high output may not be obtained. If the temperature falls below this range, the conductivity between the active materials will decrease, and the battery resistance will increase, and high output may not be obtained.

[0125] The thickness of the positive electrode is not particularly limited, but from the viewpoint of high capacity and high output, the thickness of the mixture layer minus the thickness of the metal foil of the current collector is preferably 10 μm or more, more preferably 20 μm or more, as a lower limit, and is also preferably 500 μm or less, more preferably 450 μm or less, on one side of the current collector.

[0126] The negative electrode is preferably composed of a current collector and an electrode mixture sheet containing the negative electrode active material. Examples of materials for the negative electrode current collector include metals such as copper, nickel, titanium, tantalum, and stainless steel, or alloys thereof; and carbon materials such as carbon cloth and carbon paper. Among these, metal materials, particularly copper, nickel, and alloys thereof, are preferred.

[0127] Examples of the shape of the current collector include metal foil, metal cylinder, metal coil, metal plate, expanded metal, punched metal, and foam metal in the case of a metal material, and carbon plate, carbon thin film, and carbon cylinder in the case of a carbon material. Of these, metal foil is preferred. The metal foil may be appropriately formed into a mesh shape. The thickness of the metal foil is optional, but is usually 1 μm or more, preferably 3 μm or more, and more preferably 5 μm or more, and is usually 1 mm or less, preferably 100 μm or less, and more preferably 50 μm or less. If the metal foil is thinner than this range, the strength required as a current collector may be insufficient. Conversely, if the metal foil is thicker than this range, handling may be impaired.

[0128] The negative electrode may be produced by a conventional method, for example, by laminating the electrode mixture sheet and a current collector with an adhesive therebetween, followed by vacuum drying.

[0129] The density of the negative electrode mixture is preferably 1.3 g / cm ３ More preferably, 1.4 g / cm ３ More preferably, 1.5 g / cm ３ or more, and preferably 2.0 g / cm ３ or less, more preferably 1.9 g / cm ３ More preferably, 1.8 g / cm or less ３ The range is as follows. If the temperature exceeds this range, the permeability of the electrolyte to the vicinity of the current collector / active material interface will decrease, and the charge / discharge characteristics, especially at high current densities, will decrease, and high output may not be obtained. If the temperature falls below this range, the conductivity between the active materials will decrease, and the battery resistance will increase, and high output may not be obtained.

[0130] The thickness of the negative electrode is not particularly limited, but from the viewpoint of high capacity and high output, the thickness of the mixture layer minus the thickness of the metal foil of the current collector is preferably 10 μm or more, more preferably 20 μm or more, as a lower limit, and is also preferably 500 μm or less, more preferably 450 μm or less, on one side of the current collector.

[0131] A secondary battery containing the electrolyte solution of the present disclosure preferably further includes a separator. The material and shape of the separator are not particularly limited as long as it is stable to the electrolyte solution and has excellent liquid retention properties, and any known separator can be used. Among these, it is preferable to use a material that is stable to the electrolyte solution, such as resin, glass fiber, or inorganic material, and that is in the form of a porous sheet or nonwoven fabric with excellent liquid retention properties.

[0132] Examples of materials that can be used for the resin or glass fiber separator include polyolefins such as polyethylene and polypropylene, aromatic polyamides, polytetrafluoroethylene, polyethersulfone, and glass filters. These materials may be used alone or in any combination and ratio, such as polypropylene / polyethylene two-layer films and polypropylene / polyethylene / polypropylene three-layer films. Among these, porous sheets or nonwoven fabrics made from polyolefins such as polyethylene and polypropylene are preferred for the separator, due to their excellent electrolyte permeability and shutdown effect.

[0133] The thickness of the separator is not particularly limited, but is usually 1 μm or more, preferably 5 μm or more, more preferably 8 μm or more, and usually 50 μm or less, preferably 40 μm or less, more preferably 30 μm or less. If the separator is thinner than the above range, the insulating properties and mechanical strength may be reduced. If the separator is thicker than the above range, not only may the battery performance such as rate characteristics be reduced, but also the energy density of the entire electrolyte battery may be reduced.

[0134] On the other hand, inorganic materials include, for example, oxides such as alumina and silicon dioxide, nitrides such as aluminum nitride and silicon nitride, and sulfates such as barium sulfate and calcium sulfate, and these are used in particulate or fibrous form.

[0135] As for the form, a thin film such as a nonwoven fabric, a woven fabric, or a microporous film is used. A thin film with a pore size of 0.01 to 1 μm and a thickness of 5 to 50 μm is preferably used. In addition to the above-mentioned independent thin film, a separator can be used in which a composite porous layer containing the above-mentioned inorganic particles is formed on the surface layer of the positive electrode and / or negative electrode using a resin binder. For example, a porous layer can be formed on both sides of the positive electrode using alumina particles with a 90% particle size of less than 1 μm and a fluororesin as a binder.

[0136] The material of the outer case is not particularly limited as long as it is a substance that is stable against the electrolyte used. Specifically, metals such as nickel-plated steel sheet, stainless steel, aluminum or aluminum alloy, magnesium alloy, or a laminate film of resin and aluminum foil (laminate film) can be used. From the viewpoint of weight reduction, metals such as aluminum or aluminum alloy and laminate film are preferably used.

[0137] Examples of exterior cases using metals include those in which metals are welded together to form a sealed, airtight structure by laser welding, resistance welding, or ultrasonic welding, or those in which the metals are used via a resin gasket to form a crimped structure. Examples of exterior cases using the above-mentioned laminate film include those in which resin layers are heat-sealed to form a sealed, airtight structure. In order to improve sealing properties, a resin different from the resin used in the laminate film may be interposed between the resin layers. In particular, when a sealed structure is formed by heat-sealing the resin layers via a current collecting terminal, a resin having a polar group or a modified resin into which a polar group has been introduced is preferably used as the interposed resin, since the metal and the resin are bonded together.

[0138] The shape of the secondary battery using the above-mentioned electrolyte solution is arbitrary, and examples thereof include cylindrical, prismatic, laminated, coin, large, etc. The shapes and configurations of the positive electrode, negative electrode, and separator can be changed according to the shape of each battery.

[0139] <Fluoropolyether> The present disclosure also relates to a fluoropolyether represented by the following formula (2A): (2A)R ２ -Rb ２ -O-Ra ２ -Rb ２ -R ２ (In the formula, Ra ２ is a polyoxyalkylene containing 4 to 50 oxyalkylene units and not containing fluorine; ２ Each oxyalkylene unit is independently —CH ２ CH ２ O- or -CH ２ CH(J)O—, each J is independently an alkyl group or an aryl group, and Rb ２ are each independently a fluoropolyether group represented by the following formula (4A), ２ are each independently a hydrogen atom, a hydroxyl group, a fluorine atom, an alkyl group having 1 to 3 carbon atoms, an aryl group, a carboxylic acid group, or a fluoroalkyl group having 1 to 3 carbon atoms. １ -Rf-O-Rf ２ - (wherein, Rf １ and Rf ２ are each independently an alkylene group having 1 to 16 carbon atoms which may be substituted with a fluorine atom, and Rf is a divalent fluoropolyether group.

[0140] The fluoropolyether is a novel compound that dissolves salts and has sufficient ionic conductivity, making it suitable for use as a solvent for electrolytes. Its use in electrolytes and other applications can improve the high-temperature durability (particularly the cycle performance at high temperatures) of electrochemical devices. It is also flame-retardant and has higher electrochemical stability than conventional electrolyte solvents, improving the safety of electrochemical devices. Furthermore, it also has a favorable transference number.

[0141] The preferred form of the fluoropolyether is the same as the fluoropolyether of formula (2) above.

[0142] Although the embodiments have been described above, it will be understood that various changes in form and details can be made without departing from the spirit and scope of the claims.

[0143] Next, the present disclosure will be described with reference to examples, but the present disclosure is not limited to these examples.

[0144] The following compounds were used. Compounds 1-1 to 1-9 were liquid at 25°C. <Compound 1-1> CH ３ O (CH ２ CH ２ O) ｘ１ CH ２ CF ２ (OCF ２ CF ２ ) ｙ (OCF ２ ) ｚ OCF ２ CH ２ O (CH ２ CH ２ O) ｘ２ CH ３ (x1:4, y: average 12.3, z: average 10.2, x2:4, (CH ２ CH ２ O) ｘ１ Number average molecular weight: 176, (CH ２ CH ２ O) ｘ２ Number average molecular weight: 176) <Compound 1-2> Compound having the same structure as Compound 1-1 (x1: average 8.4, y: average 12.3, z: average 10.2, x2: average 8.4, (CH ２ CH ２ O) ｘ１ Number average molecular weight: 400, (CH ２ CH ２ O) ｘ２ Number average molecular weight: 400) <Compound 1-3> CF ２ (CF ３ )CF ２ (OCF (CF ３ )CF ２ ) ｘ OCF (CF ３ ) CH２ O (CH ２ CH ２ O) ｙ CH ３ (x: average 7, y: 4, (CH ２ CH ２ O) ｙ Number average molecular weight: 176) <Compound 1-4> Compound having the same structure as Compound 1-3 (x: average 9.4, y: 4, (CH ２ CH ２ O) ｙ Number average molecular weight: 176) <Compound 1-5> Compound having the same structure as Compound 1-3 (x: average 14.3, y: 4, (CH ２ CH ２ O) ｙ Number average molecular weight: 176) <Compound 1-6> CF ３ CF ２ (OCF ２ CF ２ CF ２ ) ｘ OCF ２ CF ２ CH ２ O (CH ２ CH ２ O) ｙ CH ３ (x: average 11, y: 4, (CH ２ CH ２ O) ｙ Number average molecular weight: 176) <Compound 1-7> CF ３ CF ２ (OCF ２ CF ２ ) ｘ (OCF ２ ) ｙ OCF ２ CH ２ O (CH ２ CH ２ O) ｚ CH ３ (x: average 15.5, y: average 13.0, z: 4, (CH ２ CH ２ O) ｚ Number average molecular weight: 176) <Compound 1-8> CF ３ CF ２ (OCF ２ CF ２ ) ｘ１ (OCF２ ) ｙ１ OCF ２ CH ２ O (CH ２ CH ２ O) ｚ CH ２ CF ２ (OCF ２ CF ２ ) ｘ２ (OCF ２ ) ｙ２ OCF ２ CF ３ (x1: average 15.5, y1: average 13.0, z: average 4.1, x2: average 15.5, y2: average 13.0, (CH ２ CH ２ O) ｚ Number average molecular weight: 200) <Compound 1-9> CF ２ (CF ３ )CF ２ (OCF (CF ３ )CF ２ ) ｘ OCF (CF ３ ) CH ２ O (CH ２ CH ２ O) ｙ CH ２ C (CF ３ ) F (OCF ２ C (CF ３ ) F) ｚ OCF ２ C (CF ３ ) F ２ (x: average 7, y: average 4.1, z: average 7, (CH ２ CH ２ O) ｙ Number average molecular weight: 200)

[0145] <Compound 2-1> Ethyl methyl carbonate (EMC, manufactured by Kishida Chemical Co., Ltd.) <Compound 2-2> Polyethylene glycol 200 (manufactured by Tokyo Chemical Industry Co., Ltd.) <Compound 2-3> Poly(ethylene glycol methyl ether) 220 (manufactured by Kanto Chemical Co., Ltd.) <Compound 2-4> Fomblin Oil M07 (manufactured by Solvay) RO(CF ２ CF ２ O) ｘ (CF ２ O)ｙ R (R:CF ３ and CF ２ CF ３ are present in an average ratio of 1:0.21, x: average 29.0, y: 32.2) <Compound 2-5> Fluorolink E10H (manufactured by Solvay) HO(CH ２ CH ２ O) ｘ１ CH ２ CF ２ O (CF ２ CF ２ O) ｘ２ (CF ２ O) ｙ CF ２ CH ２ O (CH ２ CH ２ O) ｘ３ H (x1: average 1.27, y: average 8.16, x2: average 7.09, x3: average 1.27) <Compound 2-6> Fluorolink D (manufactured by Solvay) HOCH ２ CF ２ O (CF ２ CF ２ O) ｘ (CF ２ O) ｙ CF ２ CH ２ OH (x: average 12.0, y: average 10.8)

[0146] Synthesis Example 1 Synthesis of Compound 1-1 600 mg of sodium hydroxide (FUJIFILM Wako Pure Chemical Industries, Ltd., 15.3 mmol), 30 g of 1,3-bis(trifluoromethyl)benzene (Tokyo Chemical Industry Co., Ltd.), and 10 g of fluoropolyether alcohol terminated at both ends (Solvay, Fomblin D2, 5.1 mmol) were added to a nitrogen-substituted reaction vessel, followed by heating and stirring at 70°C for 3 hours. The internal temperature was raised to 65°C, and 5.5 g of triethylene glycol-2-bromoethyl methyl ether (Tokyo Chemical Industry Co., Ltd., 20.4 mmol) was added dropwise from a dropping funnel over 10 minutes, followed by heating and stirring for 6 hours. After returning to room temperature, 5 ml of 1N hydrochloric acid was added to the reaction solution and stirred for 3 hours. This solution was washed four times with pure water, and 2 g of magnesium sulfate was added to the separated organic layer and dried. The magnesium sulfate was removed by filtration, and the volatiles were removed from the treated solution by distillation. Compound 1-1 was obtained by further drying at 100°C for 3 hours.

[0147] Synthesis Example 2 Synthesis of Tosylated Polyethylene Glycol Monomethyl Ether 8.0 g of polyethylene glycol monomethyl ether 400 (Tokyo Chemical Industry Co., Ltd., average molecular weight 380-420, 20.0 mmol), 25 mL of tetrahydrofuran (Tokyo Chemical Industry Co., Ltd.), and 4.7 g of p-toluenesulfonyl chloride (Tokyo Chemical Industry Co., Ltd., 25 mmol) were added to a nitrogen-purged reaction vessel and stirred until homogeneous. A solution of 3.4 g of potassium hydroxide (Fujifilm Wako Pure Chemical Industries, Ltd., 60 mmol) in 10 mL of pure water was added to the reaction vessel in an ice-water bath. After stirring for 10 minutes, the ice-water bath was removed and the mixture was stirred at room temperature for 12 hours. The reaction solution was poured into a mixture of 30 mL of ice-water and 60 mL of methylene chloride, and the aqueous layer was extracted three times with methylene chloride. 8 g of magnesium sulfate was added to the separated organic layer and the mixture was dried. The magnesium sulfate was removed by filtration, and the volatiles were removed from the treated solution by distillation to obtain a tosylated polyethylene glycol monomethyl ether.

[0148] (Synthesis Example 3) Synthesis of Compound 1-2 Compound 1-2 was obtained by reacting the tosylated polyethylene glycol monomethyl ether synthesized in Synthesis Example 2 under the reaction conditions of Synthesis Example 1, instead of triethylene glycol-2-bromoethyl methyl ether.

[0149] Synthesis Example 4 Synthesis of Compound 1-3 600 mg of sodium hydroxide (FUJIFILM Wako Pure Chemical Industries, Ltd., 15.3 mmol), 30 g of 1,3-bis(trifluoromethyl)benzene (Tokyo Chemical Industry Co., Ltd.), and 5.1 g of fluoropolyether monoterminated alcohol (Unichem Co., Ltd., perfluoropolyether modified, molecular weight 1500, 5.1 mmol) were added to a nitrogen-purged reaction vessel, and the mixture was heated and stirred at 70°C for 3 hours. The internal temperature was raised to 65°C, and 2.8 g of triethylene glycol-2-bromoethyl methyl ether (Tokyo Chemical Industry Co., Ltd., 10.0 mmol) was added dropwise from the dropping funnel over 10 minutes, followed by heating and stirring for 6 hours. After returning to room temperature, 5 ml of 1N hydrochloric acid was added to the reaction solution and the mixture was stirred for 3 hours. This solution was washed four times with pure water, and 2 g of magnesium sulfate was added to the separated organic layer and dried. The magnesium sulfate was removed by filtration, and the volatile matter was distilled off from the treated solution, which was then dried at 100° C. for 3 hours to obtain compound 1-3.

[0150] Synthesis Example 5 Synthesis of Compound 1-4 Compound 1-4 was obtained by the same reaction as in Synthesis Example 4, except that the fluoropolyether monoterminated alcohol was replaced with a perfluoropolyether modified product, molecular weight 2000, manufactured by Unichem Co., Ltd.

[0151] Synthesis Example 6 Synthesis of Compound 1-5 Compound 1-5 was obtained by the same reaction as in Synthesis Example 4, except that the fluoropolyether monoterminated alcohol was replaced with a perfluoropolyether modified product, molecular weight 3000, manufactured by Unichem Co., Ltd.

[0152] Synthesis Example 7 Synthesis of Compound 1-6 Compound 1-6 was obtained by the same reaction as in Synthesis Example 4, except that the fluoropolyether monoterminated alcohol was replaced with Demnum SA manufactured by Daikin Industries, Ltd.

[0153] Synthesis Example 8 Synthesis of Compound 1-7 Compound 1-7 was obtained by the same reaction as in Synthesis Example 4, except that the fluoropolyether monoterminated alcohol was replaced with Fluorolink ZMF-402 manufactured by Solvay.

[0154] Synthesis Example 9 Synthesis of Polyethylene Glycol with Both Ends Tosylated 4.0 g of polyethylene glycol 200 (Tokyo Chemical Industry Co., Ltd., average molecular weight 190-210, 20.0 mmol), 25 mL of tetrahydrofuran (Tokyo Chemical Industry Co., Ltd.), and 9.4 g of p-toluenesulfonyl chloride (Tokyo Chemical Industry Co., Ltd., 50 mmol) were added to a nitrogen-purged reaction vessel and stirred until homogeneous. 6.7 g of potassium hydroxide (Fujifilm Wako Pure Chemical Industries, Ltd., 120 mmol) was added to the reaction vessel in an ice-water bath. After stirring for 10 minutes, the ice-water bath was removed and the mixture was stirred at room temperature for 12 hours. The reaction solution was poured into a mixture of 30 mL of ice water and 60 mL of methylene chloride, and the aqueous layer was extracted three times with methylene chloride. 5 g of magnesium sulfate was added to the collected organic layer and the mixture was dried. The magnesium sulfate was removed by filtration, and the volatiles were removed from the treated solution, yielding the desired polyethylene glycol with both ends tosylated.

[0155] Synthesis Example 10 Synthesis of Compound 1-8 A nitrogen-purged reaction vessel was charged with 600 mg of sodium hydroxide (FUJIFILM Wako Pure Chemical Industries, Ltd., 15.3 mmol), 30 g of 1,3-bis(trifluoromethyl)benzene (Tokyo Chemical Industry Co., Ltd.), and 20.4 g of a fluoropolyether monoterminated alcohol (Fluorolink ZMF-402, Solvay, 5.1 mmol), followed by heating and stirring at 70°C for 3 hours. The internal temperature was raised to 65°C, and 1.3 g (2.5 mmol) of the polyethylene glycol with both terminal tosylation derivatives obtained in Synthesis Example 9 was dissolved in 5 g of 1,3-bis(trifluoromethyl)benzene and added dropwise from the dropping funnel over 10 minutes. The mixture was then heated and stirred for 6 hours. After returning to room temperature, 5 ml of 1N hydrochloric acid was added to the reaction solution and the mixture was stirred for 3 hours. This solution was washed four times with pure water, and 2 g of magnesium sulfate was added to the separated organic layer, followed by drying. The magnesium sulfate was removed by filtration, and the volatile matter was distilled off from the treated solution, which was then dried at 100° C. for 3 hours to obtain compound 1-8.

[0156] Synthesis Example 11 Synthesis of Compound 1-9 Compound 1-9 was obtained by the same reaction as in Synthesis Example 10, except that the fluoropolyether monoterminated alcohol was replaced with a perfluoropolyether modified product, molecular weight 1,500, manufactured by Unichem Co., Ltd.

[0157] <Experiment 1> Examples 1 to 11 and Comparative Examples 1 to 6 (Preparation of Composition (Electrolyte Solution) Containing Lithium Salt) A compound listed as component 1 in Table 1 and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI, manufactured by Tokyo Chemical Industry Co., Ltd.), which is a lithium salt, were added and stirred at 45°C for 24 hours to obtain a composition containing 5% by mass of the lithium salt. Note that when a compound listed as component 2 in Table 1 was included, components 1 and 2 were mixed in the volume ratio listed in Table 1, and then the lithium salt was added to obtain a composition containing 5% by mass of the lithium salt.

[0158] (Non-flammability test) The non-flammability (non-ignition property) of the composition was examined by the following method. (Sample preparation) A strip of cellulose paper (15 mm wide, 320 mm long, 0.04 mm thick) was thoroughly immersed in the composition produced in the above Examples or Comparative Examples, and then removed to serve as a sample. (Test method) The sample was fixed to a metal stand, and a lighter flame was brought close to one end of the sample and held there for 1 second to check for ignition. The evaluation criteria were ○ if the sample did not ignite (non-flammable) or if it ignited but the flame quickly went out (self-extinguishing), and × if it ignited and continued to burn.

[0159] (Reduction Resistance Test) A lithium metal piece was placed in the composition and left for one week, and the discoloration of the surface of the lithium metal piece was visually observed. If there was no discoloration, it was evaluated as good reduction resistance and marked with ○, and if there was discoloration, it was evaluated as poor reduction resistance and marked with ×.

[0160] (Salt Solubility Test) The prepared composition was visually observed and rated as follows: ◯ if it was a homogeneous solution; Δ if the salt appeared to be dissolved but some of the salt remained undissolved; and × if the salt was completely insoluble.

[0161]

[0162] <Experiment 2> Examples 12 to 25, Comparative Examples 7 to 12 (Preparation of Compositions (Electrolyte Solutions) Containing Lithium Salts) Solutions were prepared in the same manner as in Experiment 1 using the combinations of compounds and salts shown in Tables 2 to 4. The salts used were as follows: LiTFSI: Lithium bis(trifluoromethanesulfonyl)imide (manufactured by Tokyo Chemical Industry Co., Ltd.) LiFSI: Lithium bis(fluorosulfonyl)imide (manufactured by Tokyo Chemical Industry Co., Ltd.) LiPF ６: Lithium hexafluorophosphate (manufactured by Kanto Denka Kogyo Co., Ltd.)

[0163] (Measurement of Ionic Conductivity) Ionic conductivity was measured using a SevenCompact S230 manufactured by Mettler Toledo at 25° C. The measuring instrument was calibrated in advance using a standard solution of 12.88 mS / cm before use.

[0164] (Li ion transport number) The Li ion transport number was determined by the following method (pulsed magnetic field gradient NMR measurement). The pulsed magnetic field gradient NMR measurement was performed at 25° C. using a JEOL JNM-ECA400WB. ７ The self-diffusion coefficient D is [where A(0) is the peak intensity when no magnetic field gradient pulse is applied, A(g) is the peak intensity at each gradient magnetic field intensity g, δ is the magnetic field gradient pulse width, Δ is the diffusion time (100 ms) of the molecule being observed, γ is the gyromagnetic ratio, and D is the diffusion coefficient.] By plotting the left side of the equation on the vertical axis and k on the horizontal axis, the diffusion coefficient D was obtained from the slope of the approximate line.

[0165] (Preparation of coin-type lithium-ion secondary battery) <Preparation of positive electrode> Li(Ni) ０．６ Mn ０．２ Co ０．２ ) O ２ 95% by weight of the cathode, 3% by weight of acetylene black as a conductive additive, and 2% by weight of polyvinylidene fluoride (PVdF) as a binder were mixed in NMP solvent to form a slurry. The resulting slurry was uniformly applied to a 20 μm thick aluminum foil, dried (110 ° C, 30 minutes), and then compressed using a press to form a positive electrode sheet integrated with the current collector, which was then punched to a predetermined size. The electrode mixture thickness was 57 μm and the density was 2.8 g / cc.

[0166] <Preparation of Negative Electrode> 98 parts by mass of a carbonaceous material (graphite) was mixed with 1 part by mass of an aqueous dispersion of sodium carboxymethylcellulose (concentration of sodium carboxymethylcellulose: 1% by mass) and 1 part by mass of an aqueous dispersion of styrene-butadiene rubber (concentration of styrene-butadiene rubber: 50% by mass) as a thickener and binder, and the mixture was mixed in a disperser to form a slurry. The resulting slurry was applied to a 10 μm thick copper foil, dried, and rolled in a press, and then punched to the desired size.

[0167] <Preparation of Coin Cell> The above-mentioned positive electrode and negative electrode were arranged opposite each other with a 20 μm-thick microporous polyethylene film (separator) interposed therebetween, and an electrolyte solution having the composition obtained in the preparation of a composition (electrolyte solution) containing a lithium salt was used as the electrolyte solution. The battery was held in a vacuum state until the above-mentioned nonaqueous electrolyte solution sufficiently permeated the separator and the like, and then the battery was sealed, pre-charged, and aged to prepare a coin-type lithium-ion secondary battery.

[0168] (Gravimetric Discharge Capacity Characteristics and High-Temperature Cycle Characteristics) The lithium ion secondary battery manufactured as described above was charged at a constant current and constant voltage (0.01 C cut) at 80°C to 4.2 V at a current equivalent to 0.05 C, and then discharged to 3 V at a constant current of 0.05 C. This constituted one cycle, and the initial discharge capacity was calculated from the discharge capacity at the third cycle. Gravimetric discharge capacity characteristics were then calculated using the following formula: - Formula for calculating gravimetric discharge capacity characteristics Gravimetric discharge capacity characteristics (mAh / g) = Initial discharge capacity (mAh) / Weight (g) of active material in positive electrode mixture The gravimetric discharge capacity characteristics were ranked as follows: A: 165 mAh / g or more B: 155 mAh / g or more but less than 165 mAh / g C: 145 mAh / g or more but less than 155 mAh / g D: Less than 145 mAh / g Thereafter, cycling was performed up to 10 cycles, and the capacity retention rate was calculated using the following formula. Formula for calculating capacity retention rate Capacity retention rate (%) = Discharge capacity after 10 cycles (mAh) / Discharge capacity after 3 cycles (mAh) × 100 The capacity retention rate (high temperature cycle characteristics) was ranked as follows: A: 95% or more B: 90% or more and less than 95% C: 85% or more and less than 90% D: Less than 85%

[0169]

[0170] In Table 2, the value with "E" indicates an exponent. For example, ".E-04" indicates "×10 －４ The same applies to Tables 3 and 4 below.

[0171]

[0172] <Preparation of Polymer Electrolyte Membrane> 10 g of polyethylene oxide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., molecular weight 1,000,000), 4 g of Compound 1-1, and 0.2 g of LiTFSI (lithium bis(trifluoromethanesulfonyl)imide) (manufactured by Tokyo Chemical Industry Co., Ltd.) as an alkali metal salt were dissolved in 10 mL of dimethylformamide, and the resulting solution was cast using an applicator and adjusted to a thickness of approximately 60 μm after drying. The cast polymer electrolyte solution was dried under reduced pressure at 100° C. for 24 hours to prepare a polymer electrolyte membrane.

[0173] <Preparation of Coin Cell Using Polymer Electrolyte Membrane> (Example 26) The positive electrode used in Example 12, the polymer electrolyte prepared above, and the negative electrode used in Example 12 were stacked in this order and rolled with a roll press to enhance adhesion. Thereafter, the cell was sealed, pre-charged, and then aged to prepare a coin-type lithium-ion secondary battery.

[0174] Comparative Example 13 A polymer electrolyte membrane was prepared in the same manner as in Example 26 except that Compound 1-1 used in Example 26 was replaced with Compound 2-2, and a coin-type lithium ion secondary battery was fabricated.

[0175] (Gravimetric Discharge Capacity Characteristics and High-Temperature Cycle Characteristics) The lithium ion secondary battery manufactured as described above was charged at a constant current and constant voltage (0.01 C cut) at 80°C to 4.2 V at a current equivalent to 0.05 C, and then discharged to 3 V at a constant current of 0.05 C. This constituted one cycle, and the initial discharge capacity was calculated from the discharge capacity at the third cycle. Gravimetric discharge capacity characteristics were then calculated using the following formula: - Formula for calculating gravimetric discharge capacity characteristics Gravimetric discharge capacity characteristics (mAh / g) = Initial discharge capacity (mAh) / Weight (g) of active material in positive electrode mixture The gravimetric discharge capacity characteristics were ranked as follows: A: 100 mAh / g or more B: 90 mAh / g or more but less than 100 mAh / g C: 80 mAh / g or more but less than 90 mAh / g D: Less than 80 mAh / g Thereafter, cycling was performed up to 10 cycles, and the capacity retention rate was calculated using the following formula. Formula for calculating capacity retention rate Capacity retention rate (%) = Discharge capacity after 10 cycles (mAh) / Discharge capacity after 3 cycles (mAh) × 100 The capacity retention rate (high temperature cycle characteristics) was ranked as follows: A: 95% or more B: 90% or more and less than 95% C: 85% or more and less than 90% D: Less than 85%

Claims

1. A composition comprising at least one fluoropolyether represented by any one of the following formulas (1) to (3) and a salt: (1) R １ -O-Ra １ -Rb １ -O-Ra １ -R １ (2) R ２ -Rb ２ -O-Ra ２ -Rb ２ -R ２ (3) R ３ -Rb ３ -O-Ra ３ -R ３ (In the formula, Ra １ ~Ra ３ are each independently a polyoxyalkylene group containing 4 to 50 oxyalkylene units not containing fluorine, １ ~Ra ３ Each oxyalkylene unit is independently —CH ２ CH ２ O- or -CH ２ CH(J)O-, each J is independently an alkyl group or an aryl group, and Rb １ ~Rb ３ R is each independently a fluoropolyether group represented by the following formula (4): １ and R ３ each independently represents a fluorine atom, an alkyl group having 1 to 3 carbon atoms, an aryl group, a carboxylic acid group, or a fluoroalkyl group having 1 to 3 carbon atoms; R ２ are each independently a hydrogen atom, a hydroxyl group, a fluorine atom, an alkyl group having 1 to 3 carbon atoms, an aryl group, a carboxylic acid group, or a fluoroalkyl group having 1 to 3 carbon atoms. １ -Rf-O-Rf ２ - (wherein, Rf １ and Rf ２ are each independently an alkylene group having 1 to 16 carbon atoms which may be substituted by a fluorine atom, and Rf is a divalent fluoropolyether group.

2. The above Ra １ ~Ra ３ The composition according to claim 1, wherein each of the groups independently represents a polyoxyalkylene group represented by the following formula (Ra-I): -(CH ２ CH ２ O)r(CH ２ CH (CH ３ )O)s(CH ２ CH (CH ２ CH ３ )O)t(CH ２ CH(Ph)O)u- (wherein r, s, t and u are each independently an integer of 0 or 1 or more, and r+s+t+u is 4 to 50.) 3. The above Ra １ ~Ra ３ The composition according to claim 1 or 2, wherein the number average molecular weight of said compound is 40 to 4,000.

4. The composition according to any one of claims 1 to 3, wherein each Rf is independently a fluoropolyether group represented by the following formula (Rf-I): Formula (Rf-I): -(OC ６ F １２ ) a-(OC ５ F １０ ) b-(OC ４ F ８ )c-(OC ３ Rc ６ ) d-(OC ２ F ４ ) e-(OCF ２ )f- (In the formula, Rc is each independently a hydrogen atom, a fluorine atom or a chlorine atom; a, b, c, d, e and f are each independently an integer from 0 to 200; the sum of a, b, c, d, e and f is 1 or more; the order of the repeating units to which a, b, c, d, e or f is assigned is arbitrary; and when all Rc are hydrogen atoms or chlorine atoms, at least one of a, b, c, e and f is 1 or more.) 5. The composition according to any one of claims 1 to 4, wherein each Rf is independently a group represented by the following formula (Rf-II) or the following formula (Rf-I-II): Formula (Rf-II): -(OC ３ F ６ ) d-(OC ２ F ４ )e- (wherein, d is an integer of 1 to 200, and e is 0 or 1.) Formula (Rf-I-II): -(OC ４ F ８ )c-(OC ３ F ６ ) d-(OC ２ F ４ ) e-(OCF ２ )f- (In the formula, c and d each independently represent an integer of 0 to 30, e and f each independently represent an integer of 1 to 200, the sum of c, d, e and f is 2 or more, and the order of each repeating unit to which c, d, e or f is added is arbitrary.) 6. The above R １ ~R ３ The composition according to any one of claims 1 to 5, wherein each of the is independently a methyl group, an ethyl group, a trifluoromethyl group, or a pentafluoroethyl group.

7. The composition according to any one of claims 1 to 6, wherein said salt is a lithium salt.

8. The composition according to any one of claims 1 to 7, wherein the content of said salt is 0.1 to 30% by mass.

9. The composition according to any one of claims 1 to 8, which is liquid at any temperature between 25°C and 80°C.

10. The composition according to any one of claims 1 to 9, wherein the content of the polyalkylene oxide represented by the following formula (5) is less than 20 mass %. (5) R １Ｂ - (OCHR １Ａ (CH ２ ) jCHR ２Ａ ) n-OR ２Ｂ (In the formula, R １Ａ and R ２Ａ are each independently a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, j is an integer of 0 or 1 to 2, and R １Ｂ and R ２Ｂ are each independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and n is an integer of 5 to 1000.

11. An electrolyte solution comprising the composition according to any one of claims 1 to 10.

12. Ion conductivity is 1.0 x 10 －７ ~1.0 x 10 －３ 12. The electrolyte according to claim 11, wherein the electrolytic solution has a viscosity of 1.0 S / cm.

13. The electrolyte according to claim 11 or 12, having a Li ion transport number of 0.2 to 0.

5.

14. A polymer electrolyte comprising the electrolytic solution according to any one of claims 11 to 13.

15. An electrochemical device comprising the electrolytic solution according to any one of claims 11 to 13 or the polymer electrolyte according to claim 14.

16. A fluoropolyether represented by the following formula (2A): (2A)R ２ -Rb ２ -O-Ra ２ -Rb ２ -R ２ (In the formula, Ra ２ is a polyoxyalkylene containing 4 to 50 oxyalkylene units not containing fluorine, ２ Each oxyalkylene unit is independently —CH ２ CH ２ O- or -CH ２ CH(J)O-, each J is independently an alkyl group or an aryl group, and Rb ２ R is each independently a fluoropolyether group represented by the following formula (4A): ２ are each independently a hydrogen atom, a hydroxyl group, a fluorine atom, an alkyl group having 1 to 3 carbon atoms, an aryl group, a carboxylic acid group, or a fluoroalkyl group having 1 to 3 carbon atoms. １ -Rf-O-Rf ２ - (wherein, Rf １ and Rf ２ are each independently an alkylene group having 1 to 16 carbon atoms which may be substituted by a fluorine atom, and Rf is a divalent fluoropolyether group.

17. The above Ra ２ The fluoropolyether according to claim 16, wherein Rf is a polyoxyalkylene group represented by the following formula (Ra-I), and each Rf is independently a group represented by the following formula (Rf-II) or (Rf-I-II). ２ CH ２ O)r-(CH ２ CH (CH ３ ) O) s-(CH ２ CH (CH ２ CH ３ ) O) t-(CH ２ CH(Ph)O)u- (wherein r, s, t and u are each independently 0 or an integer of 1 or more, and r+s+t+u is 4 to 50.) Formula (Rf-II): -(OC ３ F ６ ) d-(OC ２ F ４ )e- (wherein, d is an integer of 1 to 200, and e is 0 or 1.) Formula (Rf-I-II): -(OC ４ F ８ )c-(OC ３ F ６ ) d-(OC ２ F ４ ) e-(OCF ２ )f- (In the formula, c and d each independently represent an integer of 0 to 30, e and f each independently represent an integer of 1 to 200, the sum of c, d, e and f is 2 or more, and the order of each repeating unit to which c, d, e or f is added is arbitrary.)

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